Water tray arrangement for the dampening unit of an offset printing machine

ABSTRACT

The water tray in the dampening unit of an offset printing machine is divided by a normally upright partition into two compartments which communicate through a low aperture in the partition near the bottom wall of the tray. One compartment is upwardly sealed by a cover projecting beyond the partition to cover a portion of the other compartment which normally receives a fountain roller. The tray is releasably supported on a bracket which may be pivoted on the machine frame to drive the dampening fluid into the covered compartment when the machine is shut down.

0 United States Patent H 3,561,357

[72] Inventors lle nzJoachimschink 3,318,238 5/1967 Gottscho 101/364X n rki 1,861,142 5 1932 Scherrer 101/364 Herm nn Raib .S G rg ,Ge1-many 1,935,731 11/1933 Staude.... 118/262 pp 707,624 2,210,567 8/1940 Carroll 118/262 1 Filed F -23,1968 3,045,592 7/1962 SheareretaL. 101/364 1 Patented Feb-9, 1971 2,995,084 8 1961 Mosegaard 101 147 1 1 Assignee 3,073,240 1 1963 Tyma,.lr.,etal. 101 210 g m y 3,283,707 11 1966 Greubeletal. 101 364 1 1 Priority Apr-17,1967 3,405,636 10/1968 Schmidlin 101 148 [33] Germany 31 B92103 FOREIGN PATENTS 867,550 1953 Germany 101/350 319,962 1957 Switzerland... 101/364 [54] WATER TRAYARRANGEMENTFORTHE 692,385 1964 Canada 101/364 DAMPENING UNIT OF AN OFFSET PRINTING 148, 208, 207, 210, 350, 425, 426, 363367; 1 18/262 (lnquired); 95/(1nquired), 89 (LAM); 137/571, 574, 576

[56] References Cited UNITED STATES PATENTS 2,876,039 3/ 1959 Vogdt l01/363UX 3,145,653 8/1964 Lake 101/148X PrimaryExaminer-Robert E. Pulfrey Assistant Examiner-Eugene H. Eickholt Attorney-Kelman and Herman ABSTRACT: The water tray in the dampening unit of an offset printing machine is divided by a normally upright partition into two compartments which communicate through a low aperture in the partition near the bottom wall of the tray. One compartment is upwardly sealed by a cover projecting beyond the partition to cover a portion of the other compartment which normally receives a fountain roller. The tray is releasably supported on a bracket which may be pivoted on the machine frame to drive the dampening fluid into the covered compartment when the machine is shut down.

WATER TRAY ARRANGEMENT FOR THE DAMPENING UNIT OF AN OFFSET PRINTING MACHINE BACKGROUND OF THE INVENTION This invention relates to dampening units for offset printing machines, and particularly for office offset duplicating machines.

Offset machines of the type described are conventionally equipped with a fountain roller which dips into an acidulated aqueous dampening medium in a tray. A liquid film is transferred by intermediate rollers from the normally driven fountain roller to an axially oscillating distributing roller, and thence to a master or plate fastened on a plate cylinder of the machine. If a single distributing roller is provided, it may also receive ink from an associated inking unit.

It is necessary in conventional ofiset machines to remove the aqueous dampening fluid, hereinafter referred to as water" for the sake of simplicity, from the tray when the machine is to be shut down, as normally occurs every evening, and to clean the container. The procedure is time consuming and inconvenient because the water is sufficiently costly to warrant its being reclaimed, as by transferring it from the tray to bottles for repeated use on the next working day. The time spent in wiping the last traces of liquid from the tray is not inconsiderable.

The object of the invention is a modification of the tray arrangement in an offset printing machine of the type described which makes it unnecessary to remove the dampening medium from the tray, yet avoids contamination of the liquid by dust in the atmosphere and other contaminants, and damage to the machine by vapors released by the medium.

SUMMARY OF THE INVENTION With this object and others in view, as will hereinafter become apparent, the invention, in one of its aspects, provides the dampening unit of an offset printing or duplicating machine with a tray in which two compartments are separated by a partition transverse to the bottom wall of the tray and having an aperture near the bottom wall which connects the compartments. A cover which engages the partition and the tray seals one of the compartments. The tray is mounted on the machine frame so that it can pivot between an operative and an inoperative position. In the operative position of the tray, the two compartments are horizontally offset from each other, and a fountain roller of the machine is partly received in the other compartment. In the inoperative position of the tray, the sealed compartment is downwardly offset from the other compartment.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. I shows a tray arrangement of the invention in side elevation and partly in section, and other elements of an offset machine in a conventional manner, the tray being in the operative position;

FIG. 2 shows a portion of the apparatus of FIG. I with the tray in the inoperative position;

FIG. 3 shows the device of FIG. 2 without its tray; and

FIG. 4 illustrates the tray removed from the apparatus of FIG. 3 in a perspective view on a larger scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in detail, and initially to FIG. I, there is shown as much of an office offset duplicating machine as is needed for an understanding of this invention. A tray I is divided into two compartments la, Ib by an upright partition 1c. The compartment la is upwardly sealed by a cover 1 f which projects horizontally beyond the partition lc so as partly to cover the otherwise open compartment lb.

The tray 1 stands on the top face of a supporting bracket 2 which is attached to the machine frame I6 by a horizontal pivot pin or shaft 3. An abutment pin 4 which is parallel to the shaft 3 is horizontally slidable in a slot of the frame l6 and is partly received in a guide opening I3 of the bracket 2. A spring I2 attached to the shaft 3 tends to draw the pin 4 horizontally into either one of two pockets I3 in a vertical wall of the opening 13, and thereby arrests the bracket 2 either in the operative position shown in FIG. I or the inoperative position illustrated in FIGS. 2 and 3.

A fountain roller 5 journaled in the frame I6 dips into water 15 held in the tray I when the latter is in the operative position shown in FIG. 1, but is removed from the water when the tray 1 is swung with the bracket 2 into the inoperative position shown in FIG. 2. The roller 5 is rotated by the main drive of the machine in a conventional manner, not shown, to pick up a water film which is transferred by a ductor I7 to an axially oscillating distributing roller 8 in circumferential contact with an application roller 9 in the usual manner. The ductor 17 moves back and forth between the fountain roller 5 and the distributing roller 8 as is indicated by a curved double arrow and conventional in itself.

Ink is simultaneously supplied to the distributing roller 8 from a reservoir 6 formed between a flexible steel blade 7 and one member of a train 18 of rollers, the last of the rollers I8 transferring an ink film to the distributor roller 8 so that ink and water are jointly applied by the application roller 9 to a paper plate or master (not shown) on a plate cylinder ID for transfer of an inked image to a blanket cylinder I I.

When the machine is to be shut down, the bracket 2 is swung into the inoperative position shown in FIGS. 2 and 3, and the tray 1 is removed and positioned so that its bottom wall Id is upright and the partition Ic is horizontal, as shown in FIG. 4. The entire water contained in the tray I is thereby drained into the sealed compartment Ia through an aperture 14 in the partition 10 near the bottom wall Id. The height of the aperture 14 to its top edge 14a, as measured in the operative position of the tray 1, is smaller than the corresponding height of the circumferential wall 1e of the compartment lb so that the wall 12 extends over the opening I4 and prevents dust from falling into the water IS in the compartment Ih when the tray is in the position shown in FIG. 4.

When the tray I is again installed on the printing machine by placing it on the bracket 2 in the inoperative position of the latter, as shown in FIG. 3, and then pivoting the bracket to the position of FIG. ll, water 15 runs from the compartment la into the compartment lb until the water level in the latter is higher than the edge 14a of the aperture I4 and the pressure difference between the air trapped in the compartment Ia and the ambient atmosphere balances the difference in hydrostatic head between the two compartments. A constant water level is thereby maintained in the compartment Ib.

A single charge of water IS in the tray I is normally sufficient for a days work, and may be replenished before again installing the tray in the machine. The cover If which projects over the partition 1c forms a receptacle for the added liquid in the position of the tray illustrated in FIG. 4 until the water can pass through the aperture I4 into the compartment la. The use of disposable trays supplied with a charge of water is contemplated, and such trays may be supplied with a seal over the aperture I4 that is broken prior to use, the tray being discarded when empty.

When the tray 1 containing water 15 is removed, the dampening unit may be cleaned in a simple manner by replacing the tray I with another, closely similar tray which contains a cleaning fluid. The cleaning fluid is transferred to all operating surfaces of the inking and dampening unit when the machine is then run without ink. The ink film is gradually washed from all rollers by the cleaning fluid and collected in the cleaning tray. The cleaning operation may be accelerated by installing a special cleaning plate on the cylinder 10 in a manner known in itself.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention, and that numerous modifications and alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

We claim:

1. In an offset printing machine having a frame, a plate cylinder rotatably mounted on said frame, and a dampening unit for coating said plate cylinder with an aqueous fluid, the dampening unit including a tray arrangement adapted to hold a supply of fluid, a fountain roller arranged for partial immersion in a fluid held by said tray arrangement, and means for transferring fluid from said fountain roller to said plate cylinder, the improvement in the tray arrangement which comprises:

a. a tray member having a bottom wall;

b. a partition separating two compartments in said tray member, said partition being transverse to said bottom wall and formed with an aperture near the bottom wall connecting said compartments.

c. a cover engaging said partition and said tray member and sealing one of said compartments from the atmosphere when liquid in said tray member covers said aperture; and

. mounting means releasably mounting said tray member on said frame for pivotal movement between an operative and in inoperative position;

1. said compartments being horizontally ofl'set from each other, and said fountain roller being partly received in the liquid in the other one of said compartments when said liquid covers said aperture;

2. said one compartment being downwardly offset from said other compartment in said inoperative position of said tray member;

3. said tray member moving toward and away from said fountain roller between said positions thereof; and

4. said fountain roller being removed from said other compartment in said inoperative position of said tray member.

2. In a machine as set forth in claim I, said mounting means including a support member and a pivot securing said support member to said frame for movement about a horizontally extending axis, said support member releasably supporting said tray member.

3. In a machine as set forth in claim 2. said mounting means further including abutment means for holding said support member in each of two positions angularly offset relative to said axis, said tray member being in said operative position and in said inoperative position respectively when said support member is in one of said two angularly offset positions.

4. in a machine as set forth in claim I, said other compartment having a circumferential wall transverse of said bottom wall, the height of said circumferential wall transversely of said bottom wall being greater than the corresponding height of said aperture.

5. In a machine as set forth in claim 4, said cover projecting beyond said partition to cover a portion of said other compartment.

6. In a machine as set forth in claim 4, said other compartment being open in a direction away from said bottom wall.

7. In a machine as set forth in claim 6. means on said tray member for holding said tray member, when released from said frame, in a position in which said partition is substantially horizontal and said circumferential wall extends over said aperture. 

1. In an offset printing machine having a frame, a plate cylinder rotatably mounted on said frame, and a dampening unit for coating said plate cylinder with an aqueous fluid, the dampening unit including a tray arrangement adapted to hold a supply of fluid, a fountain roller arranged for partial immersion in a fluid held by said tray arrangement, and means for transferring fluid from said fountain roller to said plate cylinder, the improvement in the tray arrangement which comprises: a. a tray member having a bottom wall; b. a partition separating two compartments in said tray member, said partition being transverse to said bottom wall and formed with an aperture near the bottom wall connecting said compartments. c. a cover engaging said partition and said tray member and sealing one of said compartments from the atmosphere when liquid in said tray member covers said aperture; and d. mounting means releasably mounting said tray member on said frame for pivotal movement between an operative and in inoperative position;
 1. said compartments being horizontally offset from each other, and said fountain roller being partly received in the liquid in the other one of said compartments when said liquid covers said aperture;
 2. said one compartment being downwardly offset from said other compartment in said inoperative position of said tray member;
 3. said tray member moving toward and away from said fountain roller between said positions thereof; and
 4. said fountain roller being removed from said other compartment in said inoperative position of said tray member.
 2. said one compartment being downwardly offset from said other compartment in said inoperative position of said tray member;
 2. In a machine as set forth in claim 1, said mounting means including a support member and a pivot securing said support member to said frame for movement about a horizontally extending axis, said support member releasably supporting said tray member.
 3. In a machine as set forth in claim 2, said moUnting means further including abutment means for holding said support member in each of two positions angularly offset relative to said axis, said tray member being in said operative position and in said inoperative position respectively when said support member is in one of said two angularly offset positions.
 3. said tray member moving toward and away from said fountain roller between said positions thereof; and
 4. said fountain roller being removed from said other compartment in said inoperative position of said tray member.
 4. In a machine as set forth in claim 1, said other compartment having a circumferential wall transverse of said bottom wall, the height of said circumferential wall transversely of said bottom wall being greater than the corresponding height of said aperture.
 5. In a machine as set forth in claim 4, said cover projecting beyond said partition to cover a portion of said other compartment.
 6. In a machine as set forth in claim 4, said other compartment being open in a direction away from said bottom wall.
 7. In a machine as set forth in claim 6, means on said tray member for holding said tray member, when released from said frame, in a position in which said partition is substantially horizontal and said circumferential wall extends over said aperture. 